Element.getAttributeNS()

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句法
范例
注意事项
规范
浏览器兼容性
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getAttributeNS() 方法在 元素 interface returns the string value of the attribute with the specified namespace and name. If the named attribute does not exist, the value returned will either be null or "" (the empty string); see 注意事项了解细节。

句法

attrVal = element.getAttributeNS(namespace, name)

参数

namespace
名称

返回值

The string value of the specified attribute. If the attribute doesn't exist, the result is null .

注意： Earlier versions of the DOM specification had this method described as returning an empty string for non-existent attributes, but it was not typically implemented this way since null makes more sense. The DOM4 specification now says this method should return null for non-existent attributes.

范例

The following SVG document reads the value of the foo attribute in a custom namespace.

<svg xmlns="http://www.w3.org/2000/svg"
    xmlns:test="http://www.example.com/2014/test" width="40" height="40">
  <circle id="target" cx="12" cy="12" r="10" stroke="#444"
      stroke-width="2" fill="none" test:foo="Hello namespaced attribute!"/>
  <script type="text/javascript">
    var ns = 'http://www.example.com/2014/test';
    var circle = document.getElementById( 'target' );
    console.log( 'attribute test:foo: "' + circle.getAttributeNS( ns, 'foo' ) + '"' );
  </script>
</svg>

In an HTML5 document the attribute has to be accessed with test:foo since namespaces are not supported.

<!DOCTYPE html>
<html>
<body>
<svg xmlns="http://www.w3.org/2000/svg"
    xmlns:test="http://www.example.com/2014/test" width="40" height="40">
  <circle id="target" cx="12" cy="12" r="10" stroke="#444" stroke-width="2"
      fill="none" test:foo="Foo value"/>
</svg>
<script type="text/javascript">
  var ns = 'http://www.example.com/2014/test';
  var circle = document.getElementById( 'target' );
  console.log('Attribute value: ' + circle.getAttribute('test:foo'));
</script>
</body>
</html>

注意事项

Namespaces are only supported in XML documents. HTML5 documents have to use getAttribute() 代替。

getAttributeNS() 不同于 getAttribute() in that it allows you to further specify the requested attribute as being part of a particular namespace, as in the example above, where the attribute is part of the fictional "specialspace" namespace on Mozilla.

Prior to the DOM4 specification, this method was specified to return an empty string rather than null for non-existent attributes. However, most browsers instead returned null. Starting with DOM4, the specification now says to return null. However, some older browsers return an empty string. For that reason, you should use hasAttributeNS() to check for an attribute's existence prior to calling getAttributeNS() if it is possible that the requested attribute does not exist on the specified element.

DOM methods dealing with element's attributes:

Not namespace-aware, most commonly used methods	Namespace-aware variants (DOM Level 2)	DOM Level 1 methods for dealing with `Attr` nodes directly (seldom used)	DOM Level 2 namespace-aware methods for dealing with `Attr` nodes directly (seldom used)
`setAttribute` (DOM 1)	`setAttributeNS`	`setAttributeNode`	`setAttributeNodeNS`
`getAttribute` (DOM 1)	`getAttributeNS`	`getAttributeNode`	`getAttributeNodeNS`
`hasAttribute` (DOM 2)	`hasAttributeNS`	-	-
`removeAttribute` (DOM 1)	`removeAttributeNS`	`removeAttributeNode`	-

规范

规范	状态	注释
DOM The definition of 'Element.getAttributeNS()' in that specification.	实时标准
DOM (文档对象模型) 3 级核心规范 The definition of 'Element.getAttributeNS()' in that specification.	过时	Specifies that a `NOT_SUPPORTED_ERR` exception is thrown if the UA does not support the `"XML"` feature. Also specifies that `null` must be passed to have no namespace.
DOM (文档对象模型) 级别 2 核心规范 The definition of 'Element.getAttributeNS()' in that specification.	过时	初始定义

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`getAttributeNS`	Chrome Yes	Edge 12	Firefox Yes Yes Starting in Firefox 13, `null` is always returned instead of the empty string, as per the DOM4 specification. Previously, there were cases in which an empty string could be returned.	IE Yes	Opera Yes	Safari 6	WebView Android Yes	Chrome Android Yes	Firefox Android Yes	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes

图例

完整支持

另请参阅

Code snippets:getAttributeNS

元数据

最后修改： 2019 年 3 月 23 日

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句法

参数

返回值

范例

注意事项

规范

浏览器兼容性

图例

另请参阅

相关话题